Threats defined

Virus — Viruses attach to another object to replicate. Some viruses attach to files and become active when the file opens, while others reside in memory and infect files as the computer opens, modifies or creates files.

Worm — Various worms exist, but recent examples such as Sasser penetrate systems

via remotely exploitable vulnerabilities.

This form does not require user action to

activate.

Trojan — A Trojan program causes damage or unwanted system behavior but does not replicate.

Bot software — Bot software searches for vulnerabilities to infect a computer and then allows the infected systems to be remotely controlled. Bots have worm and Trojan characteristics.

Spyware — A spyware program monitors system activity, typically without a user's consent and knowledge. More malicious types may uncover passwords or personal information.

Blended/hybrid threat — These attacks combine the hallmarks of different threats, such as Trojans, viruses and worms.

Malware — Malware is a catchall term for programs with bad intentions.

Sources: Computer Associates International Inc., F-Secure Corp.,

Network Associates Technology Inc. and Symantec Corp.